This invention relates to logging equipment and, more specifically, to devices used to strip branches off harvested or felled trees.
Historically, delimbing felled or harvested trees was performed manually using axes, hand saws and powered chain saws. This method of delimbing works well on large trees with sporadic branches because the weight of a felled tree trunk will snap many of the branches off the trunk leaving a minimal amount of delimbing to be performed. When smaller trees with many branches are felled, the trunk weight is often insufficient to cause the branches to snap off. Consequently, the hand delimbing process was dangerous and unpredictable, as well as time consuming.
As a result, delimbers have been developed which strip the branches off a whole tree at the harvesting site, thereby eliminating the need for manual delimbing and drastically reducing the time necessary for delimbing. The need for a delimbing machine has grown over the years as modern forestry practice has relied on clear cutting and forest thinning through the removal of smaller trees.
A popular type of delimber is the hydro-mechanical delimber. The majority of hydro-mechanical delimbers allow for a tree to be placed in a clamping device, which is generally equipped with some type of gripping jaw. A second movable delimbing device operates on the tree stripping the branches from the tree trunk. The majority of these types of machines contain complex hydraulics and electronics and many moving parts that are susceptible to damage and wear. As a result of the high purchase and operating costs, many logging operations cannot afford to purchase such delimbers. Another disadvantage of these types of delimbers is that they only delimb one or very few trees at the same time. Several of the hydro-mechanical delimbers are discussed below.
U.S. Pat. No. 3,269,463 to Moore is directed to a hydro-mechanical delimbing device. The device comprises a sliding mast assembly having a stationary mast and a traveling mast, which is driven by a cable. Coupled to the bottom of the stationary mast is a tree-gripping and cutting mechanism. A delimbing mechanism is coupled to the bottom of the traveling mast, such that when the mast is raised to the extended position, the delimbing device travels the length of the tree stripping the branches off the tree. The delimbing mechanism includes an arcuate arm, which is pivotably mounted to surround the tree-trunk, when in the closed position. The main disadvantage of the Moore delimber is that it only processes one tree at a time. In addition, the Moore device is integrally formed with a boom. Thus, this device is expensive.
U.S. Pat. No. 4,350,189 to Duchesne is directed to a delimbing device having a telescoping boom including a gripping end and a delimbing end. The felled tree is picked-up by the delimbing end of the boom, and the butt of the tree is placed into the gripping end located at the other end of the boom. Once the tree is held in place by the gripping end, the boom is retracted allowing the delimbing blades to strip the branches from the tree. The main disadvantage of the Duchesne device is that it only processes a single tree at a time. Furthermore, loading the tree into the delimber is cumbersome, and time consuming since the butt of the tree must be placed into the gripping mechanism located at the opposite end of the lifting boom. Finally, the Duchesne device must be loaded or mounted to a carrier and must get the energy to operate from the carrier. Therefore, the Duchesne device is expensive and cumbersome to transport between jobs.
Finally, U.S. Pat. No. 3,398,774 (xe2x80x9c""774xe2x80x9d) and U.S. Pat. No. 4,382,457 (xe2x80x9c""457xe2x80x9d) to Hahn both are directed to a tree delimbing and log processing device. The device comprises a gripping mechanism at one end of a flat bed and a movable carriage, which slide along the bed parallel to the tree-trunk for stripping the branches from the tree. The gripping mechanism contains a chain saw for cutting the delimbed portion of the tree-trunk into lengths suitable for use. The movable carriage contains arcuate blades for surrounding the trunk and stripping the branches. The stripping device is powered by any mechanism suitable for moving the carriage in a forward and rearward direction. In order to place the tree into the clamping mechanism, the butt of the felled tree must be placed into a vice-like clamp formed by a fixed bottom plate and a sliding clamping plate.
The disadvantages of the ""774 and ""457 devices are twofold. First, the gripping mechanism for holding the butt of the tree is formed from a vice. Therefore, the tree butt must be carefully placed in a small opening, thereby limiting the number of trees that can be processed at a time to one. Since only a single tree can be processed at a time, the process is slow and inefficient. Secondly, and most importantly, the positioning of the delimbing carriage on the devices is such that most, if not all trees, including hardwoods cannot be delimbed by the devices. For example, when a hardwood, or any heavily branched tree is first harvested and placed into these devices, the branches keep the tree trunk from dropping into the movable delimbing carriage. This occurs because the movable delimbing carriage sits flush on the device""s bed. Because the trunk of the freshly harvested tree is lifted high above the bed by its branches, the delimbing blades cannot operate on the trunk to strip away the branches. Thus, those devices cannot operate as a delimber for heavily branched trees.
Thus, in reality, the ""774 and ""457 delimbers are made to process trunks that have already been previously delimbed, having only small short branch stubs still remaining. The ""774 and ""457 devices, although called delimbers, are really delimbed tree trunk processors. Generally, a delimbed tree trunk is placed in the delimber portion of the devices to remove short branch stubs that remain after the delimbing process. Next, the trunk is fed into a second processing portion that cuts the trunk into logs of a predetermined length. Thus, the ""774 and ""457 devices are ineffective as true delimbing devices for delimbing unprocessed felled trees and require that the harvested trees be delimbed prior to being operated on by these devices.
Thus, what is needed is a inexpensive hydro-mechanical delimbing mechanism that overcomes the disadvantages of the foregoing devices. More particularly, a hydro-mechanical delimbing device is needed that is effective in delimbing multiple trees at one time, while requiring minimal maintenance and repair.
This invention is a hydro-mechanical stroke delimbing assembly for delimbing felled trees. The assembly is formed from three main parts: 1) a flatbed frame; 2) a gripping device mounted to the frame; and 3) a delimbing carriage that is movably mounted to the frame and traverses the length of the frame while stripping limbs from a tree trunk or trunks. The blade assembly includes two delimbing arms, each carrying a semi-circular blade and pivots on parallel shafts between: (1) an open position with the arms and blades separated from the path along which tree trunks move in order to sheer off the limbs; and (2) a closed position with the blades positioned near either side of that path. The delimbing carriage is movable through the use of a cable that pulls the carriage forward and backward along the flatbed frame. The gripping device and delimbing carriage are controlled from a knuckle boom loader allowing a single person to operate the knuckle boom loader and the delimbing device simultaneously.
It is a primary object of this invention to provide the logging industry with a hydro-mechanical delimbing device that:
is durable and easy to operate;
is not susceptible to jamming and requires little maintenance and repair;
is inexpensive to operate;
can delimb multiple trees at one time; and
can delimb hardwood trees.
Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings.